physics of stars

Stars are giant balls of hot, glowing gases, mainly hydrogen and helium, held together by gravity. In their cores, intense pressure and temperature enable nuclear fusion—hydrogen atoms fuse into helium, releasing enormous energy as light and heat. This energy radiates outward, balancing gravity's inward pull and keeping the star stable. Over time, stars change as they use up their fuel: some expand into red giants, others become dense remnants like white dwarfs, neutron stars, or black holes. Ultimately, a star's life cycle depends on its initial mass and composition, shaping its evolution and lifespan.